1. Field of the Invention
The present invention relates to a method of plating a doctor blade. More specifically, the present invention relates to an efficient continuous plating method for doctor blades especially used for gravure (intaglio) printing, which provides the doctor blades having a coat excellent in-abrasion resistance, and the present invention also relates to an apparatus therefor.
2. Description of the Related Art
In gravure (intaglio) printing, ink adhered to a non-image portion of a plate barrel is scraped away while a doctor blade is pressed against the circumferential surface of the plate barrel by a predetermined pressure. The doctor blade removes the ink on the non-image portion completely and has a function to leave a predetermined amount of ink on an image portion. Accordingly, the contact pressure between the plate barrel and the doctor blade must be always maintained at a predetermined level and a distal end portion of the doctor blade is required to have abrasion resistance.
One of methods for providing abrasion resistance to the distal end portion of the doctor blade is to form a ceramic plating layer on that portion.
This method is comprised of: adding an appropriate amount of ceramic fine powder such as silicon carbide or boron nitride to an electroless nickel bath or electric nickel bath; plating under agitation; depositing and compounding these fine powder into a plating film simultaneously with the plating; and baking the plating film as required to form a hard layer on the surface of the doctor blade.
The size of the doctor blade to be installed in a printing machine conforms to the width of a roll of the plate barrel (such as 50, 90, 120 or 400 cm). The width of the blade itself is, for example, 45, 50 or 60 mm. To carry out composite plating on these blades efficiently, a belt-like steel base material has been directly plated under a state rolled in a roll shape through a spacer (such as a steel material) that does not affect an edge portion of the blade. Thereafter, the roll of the base material has been unrolled and cut to a predetermined length to obtain a doctor blade (Japanese Patent Application Laid-open No. Hei 4-70343).
This method has the following problems:
(1) Since the spacer is used, the marks of an unplated spacer portion are left behind as a net pattern, thereby impairing the outer appearance of a product, and the product has a durability problem because the unplated portion is easy to rust;
(2) Since plating is carried out in a state that the base material is rolled, a forming effect at the time of plating remains when the base material is unrolled after plating. Therefore, a slightly curled product is obtained, a blade obtained by cutting the base material to a predetermined length has a slight warp (deformation), and contact pressure to a printing roll at both end portions is slightly different from contact pressure at a central portion. As a result, a locally abnormal weight loss is induced and printing cannot be made satisfactorily;
(3) Since the base material wound spirally is pre-treated, plated and post-treated as a set, generally, the production of doctor blade may only be made manually in the batch manner. Therefore, the mass-production of the doctor blade requires much labor. Further, an examination that secures removal of ceramic fine powder adhered to the edge of the blade and the step of polishing the edge of the blade both of which are carried out before the shipment of products must be carried out separately from a plating step; and
(4) Since not only the edge of the blade which is required functionally but also other portions of the doctor blade are uniformly plated, the consumption of an expensive chemical is large, thereby presenting a cost problem.
The inventor of the present invention has made an intensive study to overcome the above problems in the ceramic plating of a doctor blade of the prior art and has accomplished the present invention.
It is therefore an object of the present invention to provide a method of plating the doctor blade and an apparatus therefor which overcome the above problems in the ceramic plating of the doctor blade.
In other words, the present invention provides a continuous ceramic composite plating method for long doctor base materials and an apparatus therefor, having the following constitutions.
1) A continuous ceramic composite plating method for long doctor base materials is characterized by comprising a degreasing step, rinsing step, acid immersion step, rinsing step, electroless ceramic composite nickel plating step, plating solution collection step, rinsing step, and drying step between a first step of supplying continuously a long doctor blade base material (2) held on a material reel (1) spirally while the blade surface is maintained in a horizontal direction with respect to the surface of a solution and a final step of taking up continuously the blade base material (2) on a corresponding take-up reel (30) while the blade base material (2) is cramped by a plurality of pinch rolls (20).
2) A continuous ceramic composite plating method for long doctor base materials is characterized by comprising a degreasing step, rinsing step, acid immersion step, rinsing step, electroless ceramic composite nickel plating step, plating solution collection step, rinsing step, and drying step between a first step of supplying continuously a plurality of long doctor blade base materials (2a, 2b, 2c) held on a plurality of material reels (1a, 1b, 1c) spirally while the blade surfaces are maintained in a horizontal direction with respect to the surface of a solution , and a predetermined interval therebetween is maintained and a final step of taking up continuously the plurality of doctor blade base materials (2a, 2b, 2c) on a plurality of corresponding take-up reels (30a, 30b, 30c) while the plurality of blade base materials (2a, 2b, 2c) are cramped by a plurality of pinch rolls (20).
3) The continuous ceramic composite plating method described in the above item 1) or 2) is characterized in that the doctor blade base materials are of a double-edged type, supplied from the material reels with a central portion other than both edge portions masked in a belt form, and taken up on take-up reels.
4) A continuous ceramic composite plating method for long doctor base materials is characterized by comprising letting out the long doctor base materials plated by the method described in any one of the above items 1) to 3) from the take-up reels, straightening out and baking the long doctor base materials by passing through a heating furnace.
5) A continuous ceramic composite plating apparatus for long doctor base materials, including one or a plurality of material reels (1 or 1a, 1b, 1c) for holding one or a plurality of long blade base materials (2 or 2a, 2b, 2c) spirally, a plurality of pinch rolls (20) for cramping and forwardly supplying the one or plurality of blade base materials continuously while the blade surface(s) of the one or plurality of blade base materials are maintained in a horizontal direction with respect to the surface of a solution and a predetermined interval therebetween is maintained, the same number of take-up reels (30 or 30a, 30b, 30c) for taking up the one or plurality of blades continuously, is characterized by comprising a degreasing tank (3), rinsing tank (4), acid immersion tank (5), rinsing tank (6), electroless ceramic composite nickel plating tank (7), plating solution collecting tank (8), rinsing tank (9), and drying tank (10) between the material reels and the take-up reels.
6) The doctor blade plating apparatus described in the above item 5) is characterized in that a space tank (12) is disposed between the respective treatment tanks, and a partition plate having a slit portion (14) through which a single blade can pass or a plurality of parallel slit portions (14a, 14b, 14c) through which a plurality of blades can pass with maintaining a predetermined interval therebetween is used to separate each treatment tank from each space tank.
7) An apparatus for continuously producing baked long doctor materials is characterized by comprising a plurality of pinch rolls (20) for continuously forwardly straightening out long doctor materials plated by the method described in the above item 1) or 2), from the take-up reel and a straightening furnace for baking through which the straightened plated blades pass.